The new study, involving the same visual memory test used in the previous research, revealed that both brain processes the capacity to ignore irrelevant information and the ability to process information quickly -- diminished with age and, in fact, worked in tandem. The participants had trouble suppressing unnecessary information, but only because the speed with which they processed the irrelevant data decreased. Significantly, the slow down in processing time happened only in the very early stages of visual processing -- within 200 milliseconds.
"The study showed that the brains of older adults have a deficit in suppressing irrelevant information during visual working memory encoding, but only in the first tenth to two tenths of a second of visual processing," says the lead author of the study, Adam Gazzaley, MD, PhD, assistant professor of neurology, a member of the UCSF Memory and Aging Center and director of the UCSF Neuroscience Imaging Center.
Moreover, despite the aging brain's ability to suppress extraneous information in the ensuing milliseconds, the memory deficit persists, implying, he says, that interference by irrelevant information apparently overwhelms a limited working memory capacity, which is the ability to hold information in mind for brief periods of time to guide your actions.
As to what causes the break down in inhibition and processing speed, scientists do not know. They do know that, in the course of aging, there are changes in the structure of neurons, the density of neural tissue and the actions of ne
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University of California - San Francisco